Volume 3, Issue 1 — Year 2026 — Article e100058

ISSN (Online): 3115-8129 Biannually

Granite Rock Mass Characterization using GSI and Q-System: A Case Study for Keno-Kouh, Western Iran

Article Type: Case Study
Pages: e100058
DOI: https://doi.org/10.22034/CGEL.3.1.e100058
Crossmark
Open Access
Authors
Affiliations
  1. Department of Geology, Islamic Azad University, Zahedan Branch, Zahedan 9816743545, Iran
  2. Department of Earth Sciences, University of Tabriz, Tabriz 5166616471, Iran
Corresponding author
Email: e-asghari@tabrizu.ac.ir
ORCID: 0000-0003-0408-6107
Received: 25 February 2026 / Accepted: 14 April 2026 / Published: 25 May 2026
Abstract

The accurate classification of rock masses plays a critical role in the design and safety of geotechnical and tunneling projects. Among the most widely used systems for rock mass characterization are the Geological Strength Index (GSI) and the Rock Mass Quality index (Q-system), both of which integrate various structural and geomechanical parameters. This study focuses on evaluating the empirical relationship between GSI and Q-system in granitic rock masses of the Keno-Kouh region, situated in western Iran. Field investigations were conducted at multiple granite exposures, where joint conditions, discontinuity spacing, roughness, alteration, and rock strength were systematically measured. GSI values were derived from both direct field assessments and estimation charts, while Q-values were calculated using Barton’s classification system. A statistical correlation analysis was performed between GSI and Q-values to identify a mathematical relationship relevant to this specific lithological setting. The findings demonstrate a strong linear correlation (R²>0.85) between the two classification systems within the granitic units, highlighting the isotropic and relatively homogeneous nature of the Keno-Kouh granites. The regression equations developed in this study provide a practical tool for estimating one index based on the other, which can be especially useful in data-limited engineering scenarios.

Keywords

Rock mass, Geological strength index, Q-System, Granite, Keno-Kouh region

Data availability statement

The data supporting the findings of this study are available from the corresponding author upon reasonable request. No publicly archived dataset was generated.

Funding

This research received no external funding.

Highlights
  • GSI–Q correlation in Keno-Kouh granites
  • Granitic rocks show homogeneous behavior
  • Results support design and estimation in project
References
  1. Abad S., Mohamad E.T., Komoo I., Kalatehjari R. (2015). A typical weathering profile of granitic rock in Johor, Malaysia based on joint characterization. Arabian Journal of Geosciences, 8, 2191-2201.
  2. Abbas N., Li K.G., Emad M.Z., Khan A. (2024). Quantifying uncertainty in rock mass properties: Implications for GSI, RMi, and RMR assessments. Journal of the Southern African Institute of Mining and Metallurgy, 124(5), 285-291. https://doi.org/10.17159/2411-9717/2599/2024.
  3. Aghanabati A. (2012). Geology of Iran. Geological Survey and Mineral Exploration of Iran press, Tehran, Iran.
  4. Agliardi F., Sapigni M., Crosta G.B. (2016). Rock mass characterization by high-resolution sonic and GSI borehole logging. Rock Mechanics and Rock Engineering, 49, 4303-4318. https://doi.org/10.1007/s00603-016-1025-x.
  5. Aksoy C.O., Geniş M., Aldaş G.U., Özacar V., Özer S.C., Yılmaz Ö. (2012). A comparative study of the determination of rock mass deformation modulus by using different empirical approaches. Engineering Geology, 131, 19-28. https://doi.org/10.1016/j.enggeo.2012.01.009.
  6. Anees M., Sosa G., Van den Kerkhof A., Leiss B., Kley J., Shah M.M., Weydt L. (2024). Granitoids of the western Himalaya and Karakoram as potential geothermal reservoirs–A petrological, geochemical and petrophysical study. Geothermics, 121, 103040. https://doi.org/10.1016/j.geothermics.2024.103040.
  7. Azarafza M., Akgün H., Asghari-Kaljahi E. (2017). Assessment of rock slope stability by slope mass rating (SMR): a case study for the gas flare site in Assalouyeh, South of Iran. Geomechanics and Engineering, 13(4), 571-584. https://doi.org/10.12989/gae.2017.13.4.571.
  8. Azarafza M., Koçkar M.K., Zhu H.H. (2022). Correlations of SMR-Qslope data in stability classification of discontinuous rock slope: a modified relationship considering the iranian data. Geotechnical and Geological Engineering, 40(4), 1751-1764. https://doi.org/10.1007/s10706-021-01991-w.
  9. Azarafza M., Nanehkaran Y.A., Rajabion L., Akgün H., Rahnamarad J., Derakhshani R., Raoof A. (2020). Application of the modified Q-slope classification system for sedimentary rock slope stability assessment in Iran. Engineering Geology, 264, 105349. https://doi.org/10.1016/j.enggeo.2019.105349.
  10. Babendererde S., Hoek E., Marinos P., Cardoso A.S. (2004). Characterization of granite and the underground construction in metro do Porto, Portugal. In: Proceedings ISC-2 on Geotechnical and Geophysical Site Characterization, Millpress, Rotterdam, 1, 39-48.
  11. Bagde M.N., Raina A.K., Chakraborty A.K., Jethwa J.L. (2002). Rock mass characterization by fractal dimension. Engineering Geology, 63(1-2), 141-155. https://doi.org/10.1016/S0013-7952(01)00078-3.
  12. Baharvand S., Rahnamarad J., Soori S. (2019). Evaluation and Preparation of Seismic Zone Maps of Khorramabad City using a Hierarchical-Fuzzy Method. Geography and Environmental Planning, 30(2), 75-90. https://doi.org/10.22108/gep.2019.117074.1159.
  13. Baharvandi K., Khorshiddoust A.M., Zavareh M.N. (2021). The Clarification of Climactic Fluctuations through SNHT Method (Case Study: Khorramabad Station). Journal of Geography and Planning, 25(75), 51-63.
  14. Bar N., Barton N. (2017). The Q-slope method for rock slope engineering. Rock Mechanics and Rock Engineering, 50, 3307-3322. https://doi.org/10.1007/s00603-017-1305-0.
  15. Barton N. (2002). Some new Q-value correlations to assist in site characterisation and tunnel design. International Journal of Rock Mechanics and Mining Sciences, 39(2), 185-216. https://doi.org/10.1016/S1365-1609(02)00011-4.
  16. Barton N., Grimstad E. (2014). Tunnel and cavern support selection in Norway, based on rock mass classification with the Q-system. Norwegian Tunnelling Society, 23, 45-77.
  17. Barton N., Lien R., Lunde J.J.R.M. (1974). Engineering classification of rock masses for the design of tunnel support. Rock Mechanics, 6, 189-236.
  18. Cai M., Kaiser P.K., Tasaka Y., Minami M. (2007). Determination of residual strength parameters of jointed rock masses using the GSI system. International Journal of Rock Mechanics and Mining Sciences, 44(2), 247-265. https://doi.org/10.1016/j.ijrmms.2006.07.005.
  19. Cai M., Kaiser P.K., Uno H., Tasaka Y., Minami M. (2004). Estimation of rock mass deformation modulus and strength of jointed hard rock masses using the GSI system. International Journal of Rock Mechanics and Mining Sciences, 41(1), 3-19. https://doi.org/10.1016/S1365-1609(03)00025-X.
  20. Geological Survey of Iran (2009). Geological map and information for Keno-Kouh region, scale 1:100,000. Geological Survey and Mineral Exploration of Iran, maps unit, Tehran, Iran.
  21. Goel R.K., Singh B. (2011). Engineering Rock Mass Classification: Tunnelling, Foundations and Landslides. Butterworth-Heinemann, Oxford, England, UK.
  22. Grimstad E., Kankes K., Bhasin R., Magnussen A.W., Kaynia A. (2002). Rock mass quality Q used in designing reinforced ribs of sprayed concrete and energy absorption. Report, Norwegian Geotechnical Institute, no. 19.
  23. Hajiazizi M., Khatami R.S. (2013). Seismic analysis of the rock mass classification in the Q-system. International Journal of Rock Mechanics and Mining Sciences, 62, 123-130. https://doi.org/10.1016/j.ijrmms.2013.05.003.
  24. Hashemi M., Moghaddas S., Ajalloeian R. (2010). Application of rock mass characterization for determining the mechanical properties of rock mass: a comparative study. Rock Mechanics and Rock Engineering, 43, 305-320. https://doi.org/10.1007/s00603-009-0048-y.
  25. Hoek E., Marinos P., Benissi M. (1998). Applicability of the Geological Strength Index (GSI) classification for very weak and sheared rock masses. The case of the Athens Schist Formation. Bulletin of Engineering Geology and the Environment, 57, 151-160. https://doi.org/10.1007/s100640050031.
  26. Høien A.H., Nilsen B., Olsson R. (2019). Main aspects of deformation and rock support in Norwegian road tunnels. Tunnelling and Underground Space Technology, 86, 262-278. https://doi.org/10.1016/j.tust.2019.01.026.
  27. Hudson J.A., Harrison J.P. (1997). Engineering Rock Mechanics: An Introduction to the Principles. Pergamon, Oxford, England, UK.
  28. Hussian S., Mohammad N., Ur Rehman Z., Khan N.M., Shahzada K., Ali S., Sherin S. (2020). Review of the geological strength index (GSI) as an empirical classification and rock mass property estimation tool: Origination, modifications, applications, and limitations. Advances in Civil Engineering, 2020(1), 6471837. https://doi.org/10.1155/2020/6471837.
  29. Iran Meteorological Organization (2024). Meteorological data from Khorramabad meteorological station. Weather forecast unit, Khorramabad, Iran. Available at: https://www.irimo.ir/
  30. Jaiswal A., Verma A.K., Singh T.N. (2024). A critical review of rock mass classification systems for assessing the stability condition of rock slopes. Environmental Earth Sciences, 83(8), 245. https://doi.org/10.1007/s12665-024-11532-2.
  31. Jing L. (2003). A review of techniques, advances and outstanding issues in numerical modelling for rock mechanics and rock engineering. International Journal of Rock Mechanics and Mining Sciences, 40(3), 283-353. https://doi.org/10.1016/S1365-1609(03)00013-3.
  32. Khamehchiyan M., Dizadji M.R., Esmaeili M. (2014). Application of rock mass index (RMi) to the rock mass excavatability assessment in open face excavations. Geomechanics and Geoengineering, 9(1), 63-71. https://doi.org/10.1080/17486025.2013.806996.
  33. Lin D., Lou F., Yuan R., Shang Y., Zhao Y., Ma J., Bao W. (2017a). Rock mass characterization for shallow granite by integrating rock core indices and seismic velocity. International Journal of Rock Mechanics and Mining Sciences, 93, 130-137. https://doi.org/10.1016/j.ijrmms.2016.08.007.
  34. Lin F., Luan H., Zeng Y., Zhong Z. (2017b). Some new correlations of Q-value with rock mechanics parameters in underground oil storage caverns. Civil Engineering Journal, 3(8), 537-546. https://doi.org/10.28991/cej-2017-00000111.
  35. Ma D., Li Q., Zhang J., Liu Y., Hou, W. (2023). Pore structure characterization and nonlinear seepage characteristics of rock mass in fault fracture zones. Journal of China Coal Society, 48(2), 666-677.
  36. Mao Y., Azarafza M., Bonab M.H., Bascompta M., Nanehkaran Y.A. (2023a). Empirical correlation for in-situ deformation modulus of sedimentary rock slope mass and support system recommendation using the Qslope method. Geomechanics and Engineering, 35(5), 539-554. https://doi.org/10.12989/gae.2023.35.5.539.
  37. Mao Y., Chen L., Nanehkaran Y.A., Azarafza M., Derakhshani R. (2023b). Fuzzy-based intelligent model for rapid rock slope stability analysis using Qslope. Water, 15(16), 2949. https://doi.org/10.3390/w15162949.
  38. Marinos, V.I., Marinos P., Hoek E. (2005). The geological strength index: applications and limitations. Bulletin of Engineering Geology and the Environment, 64, 55-65. https://doi.org/10.1007/s10064-004-0270-5.
  39. Moghadam H.S., Li X.H., Ling X.X., Stern R.J., Santos J.F., Meinhold G., Shahabi S. (2015). Petrogenesis and tectonic implications of Late Carboniferous A-type granites and gabbronorites in NW Iran: Geochronological and geochemical constraints. Lithos, 212, 266-279. https://doi.org/10.1016/j.lithos.2014.11.009.
  40. Morelli G.L. (2015). Variability of the GSI index estimated from different quantitative methods. Geotechnical and Geological Engineering, 33(4), 983-995. https://doi.org/10.1007/s10706-015-9880-x.
  41. Palmström A. (1996a). Characterizing rock masses by the RMi for use in practical rock engineering: Part 1: The development of the Rock Mass index (RMi). Tunnelling and Underground Space Technology, 11(2), 175-188. https://doi.org/10.1016/0886-7798(96)00015-6.
  42. Palmström A. (1996b). Characterizing rock masses by the RMi for use in practical rock engineering, part 2: some practical applications of the rock mass index (RMi). Tunnelling and Underground Space Technology, 11(3), 287-303. https://doi.org/10.1016/0886-7798(96)00028-4.
  43. Palmström A., Broch E. (2006). Use and misuse of rock mass classification systems with particular reference to the Q-system. Tunnelling and Underground Space Technology, 21(6), 575-593. https://doi.org/10.1016/j.tust.2005.10.005.
  44. Park J.S., Go Y.W., Oh T.M. (2025). Evaluating the relationship between RMR and Q-system for improved classification of faulted rocks and weak rocks. Scientific Reports, 15(1), 1-13. https://doi.org/10.1038/s41598-025-01985-1.
  45. Pepe G., Piazza M., Cevasco A. (2015). Geomechanical characterization of a highly heterogeneous flysch rock mass by means of the GSI method. Bulletin of Engineering Geology and the Environment, 74, 465-477. https://doi.org/10.1007/s10064-014-0642-4.
  46. Qazi A., Singh K. (2023). Rock mass classification techniques and parameters: a review. Journal of Mining and Environment, 14(1), 155-178. https://doi.org/10.22044/jme.2023.12618.2292.
  47. Rehman H., Ali W., Naji A.M., Kim J.J., Abdullah R.A., Yoo H.K. (2018). Review of rock-mass rating and tunneling quality index systems for tunnel design: Development, refinement, application and limitation. Applied Sciences, 8(8), 1250. https://doi.org/10.3390/app8081250.
  48. Renani H.R., Cai M. (2022). Forty-year review of the Hoek–Brown failure criterion for jointed rock masses. Rock Mechanics and Rock Engineering, 55(1), 439-461. https://doi.org/10.1007/s00603-021-02661-2.
  49. Rezaei M., Mousavi S.Z.S. (2024). Slope stability analysis of an open pit mine with considering the weathering agent: Field, laboratory and numerical studies. Engineering Geology, 333, 107503. https://doi.org/10.1016/j.enggeo.2024.107503.
  50. Russo G. (2009). A new rational method for calculating the GSI. Tunnelling and Underground Space Technology, 24(1), 103-111. https://doi.org/10.1016/j.tust.2008.03.002.
  51. Salmanfarsi A.F., Awang H. (2025). Rock Mass Classification and Geo-resistivity Properties of Granite from Pahang, Malaysia. Construction, 5(1), 1-17.
  52. Siddique T. (2024). Rock mass classification in slope engineering with special emphasis on Slope mass rating: Current status and future projections. Geological Journal, 59(9), 2472-2486. https://doi.org/10.1002/gj.4933.
  53. Singh J.L., Tamrakar N.K. (2013). Rock mass rating and geological strength index of rock masses of Thopal-Malekhu river areas, Central Nepal lesser Himalaya. Bulletin of the Department of Geology, 16, 29-42. https://doi.org/10.3126/bdg.v16i0.8882.
  54. Somodi G., Bar N., Kovács L., Arrieta M., Török Á., Vásárhelyi B. (2021). Study of rock mass rating (RMR) and Geological Strength index (GSI) correlations in granite, siltstone, sandstone and quartzite rock masses. Applied Sciences, 11(8), 3351. https://doi.org/10.3390/app11083351.
  55. Song Y., Xue H. (2021). Correlations between rock mass intactness index (Kv) and other rock mass classification indices (RMR89 system and GSI). Bulletin of Engineering Geology and the Environment, 80, 7807-7816. https://doi.org/10.1007/s10064-021-02395-z.
  56. Sonmez H., Gokceoglu C., Ulusay R. (2004). Indirect determination of the modulus of deformation of rock masses based on the GSI system. International Journal of Rock Mechanics and Mining Sciences, 41(5), 849-857. https://doi.org/10.1016/j.ijrmms.2003.01.006.
  57. Sonmez H., Ulusay R. (1999). Modifications to the geological strength index (GSI) and their applicability to stability of slopes. International Journal of Rock Mechanics and Mining Sciences, 36(6), 743-760. https://doi.org/10.1016/S0148-9062(99)00043-1.
  58. Tavakoli J., Behnia M., Cheraghi S.M. (2018). Estimation of Rock Block Size Distribution with Distinct Element Method (DEM) using Geological Strength Index (GSI). Journal of Engineering Geology, 12(2), 259-276.
  59. Ulusay R. (2014). The ISRM Suggested Methods for Rock Characterization, Testing and Monitoring: 2007-2014. Springer, Heidelberg, Germany.
  60. Villeneuve M.C., Heap M.J., Kushnir A.R., Qin T., Baud P., Zhou G., Xu T. (2018). Estimating in situ rock mass strength and elastic modulus of granite from the Soultz-sous-Forêts geothermal reservoir (France). Geothermal Energy, 6, 1-29. https://doi.org/10.1186/s40517-018-0096-1.
  61. Wu P.K.K., Chan C.T.H., Tsui R.W.S. (2024). A review of the Q-System and the GSI based on recent tunnel and Cavern Projects in Hong Kong. Rock Mechanics and Rock Engineering, pp. 1-13. https://doi.org/10.1007/s00603-024-04158-0.
  62. Yang S., Liu S., Zhang N., Li G., Zhang J. (2021). A fully automatic-image-based approach to quantifying the geological strength index of underground rock mass. International Journal of Rock Mechanics and Mining Sciences, 140, 104585. https://doi.org/10.1016/j.ijrmms.2020.104585.
  63. Yan-jun S., Rui-xin Y., Geng-she Y., Guang-li X., Shan-yong W. (2017). Comparisons of evaluation factors and application effects of the new [BQ]GSI system with international rock mass classification systems. Geotechnical and Geological Engineering, 35, 2523-2548. https://doi.org/10.1007/s10706-017-0259-z.
  64. Yilmaz O., Unlu T. (2013). Three dimensional numerical rock damage analysis under blasting load. Tunnelling and Underground Space Technology, 38, 266-278. https://doi.org/10.1016/j.tust.2013.07.007.
  65. Yoon Y.K., Lee H.W. (2017). A study of the relationships among RMR, Q-system and GSI applied to classify rock mass of limestone mine. Explosives and Blasting, 35(4), 27-35.
  66. Zhang Y., Liu X., Liu X., Wang S., Ren F. (2019). Numerical characterization for rock mass integrating GSI/Hoek-Brown system and synthetic rock mass method. Journal of Structural Geology, 126, 318-329. https://doi.org/10.1016/j.jsg.2019.06.017.
  67. Zhang Y., Ren F.Y., Yang T.H., Wang S.Y., Zhang W.F., Yu M.X. (2018). An improved rock mass characterization method using a quantified geological strength index and synthetic rock mass model. Rock Mechanics and Rock Engineering, 51, 3521-3536. https://doi.org/10.1007/s00603-018-1532-z.
  68. Zolfaghari A., Bidar A.S., Javan M.M., Haftani M., Mehinrad A. (2015). Evaluation of rock mass improvement due to cement grouting by Q-system at Bakhtiary dam site. International Journal of Rock Mechanics and Mining Sciences, 74, 38-44. https://doi.org/10.1016/j.ijrmms.2014.12.004.
  69. Zoorabadi M., Indraratna B., Nemcik J. (2012). A new equation for the equivalent hydraulic conductivity of rock mass around a tunnel. International Journal of Rock Mechanics and Mining Sciences, 54, 125-128. https://doi.org/10.1016/j.ijrmms.2012.05.017.
How to cite
Jafarian, M., & Asghari-Kaljahi, E. (2026). Granite Rock Mass Characterization using GSI and Q-System: A Case Study for Keno-Kouh, Western Iran. Civil and Geoengineering Letters, 3(1), e100058. https://doi.org/10.22034/CGEL.3.1.e100058
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